Depth charge having rocket motor propulsion



June 27, 1961 'N. H. ENGBORG ETAL 2,989,919

DEPTH CHARGE HAVING ROCKET MOTOR PROPULSION Filed March 21, 1960 INVENTORS "11.5 HARRY E GB LARS RM' GUSTAFSSON FIG. I F H ArrmNErs United States Patent 2,989,919 DEPTH CHARGE HAVING ROCKET MOTOR PROPULSION Nils Harry Engborg and Lars Erik Gustafsson, Karlskoga,

Sweden, assignors to Akfiebolaget Bofors, Bofors, Sweden, a corporation of Sweden Filed Mar. 21, 1960, Ser. No. 16,370' Claims priority, application Sweden Mar. 21, 1959 4 Claims. (Cl. 102-7) This invention relates to depth charges and, more particularly, to a depth charge propelled by a rocket motor having at least two operating speeds.

Ordinarily, the greatest horizontal range of a depth charge is determined by the energy content of the rocket motor, so that the rocket motor should, preferably, contain the greatest possible quantity of fuel in relation to the internal weight. In launching such depth charges against targets near the launching site, it is often desir able or necessary to fire the depth charge at a rate of speed lower than the maximum rate of speed provided by the motor. This can be achieved, for example, by having the motor divided into two sections and igniting only one section thereof. In such an arrangement, the maximum rate of speed is attained by igniting both sections. It is evident, however, that with the same total weight, such a rocket motor will contain less propellant than a motor with a single section, as walls are required between the separate sections as well as an extra nozzle. Such extra material thereby reduces the maximum range of the depth charge. The maximum range of such depth charge is still further reduced if, for instance, three different rates of speed are provided for the depth charge. It is therefore an object of the present invent-ion to provide a depth charge of the above type, where a rate of speed lower than the maximum possible rate of speed can be achieved without an essential reduction in the maximum speed and without involving complicated rocket motor technical problems.

Another object of the present invention is to provide a rocket motor propelled depth charge of the type described which is extremely simple in construction, efliciently arranged in terms of fuel-capacity-to-overall-weight, and which employs rocket motor parts that are substantially foolproof in operation.

These objects and still further advantages of the present invention are achieved by providing the front part of the rocket motor with control exhaust channels which open outwardly toward the front part of the depth charge and which provide for the relief of propellant gases from the rocket motor. All of the foregoing and still further advantages of the present invention will become readily apparent from the detailed review of the following specification and drawing in which:

FIGURE 1 is a longitudinal cross sectional view of a depth charge made in accordance with the present invention;

FIGURE 2 is an enlarged fragmentary cross sectional view of certain parts of the present invention shown in FIGURE 1; and

FIGURE 3 is a view similar to FIGURE 2, with the parts in an adjusted position.

Referring now more in detail to the drawing, a depth charge made in accordance with the present invention is shown to include an outer casing 1 within which a bursting charge 2, such as TNT, a fuse 3, and a rocket motor 4, are encased.

The rocket motor 4 contains two propellant charges 5, 6, one such charge 5 generating propellant gases which flow outwardly through a nozzle 7, and the other charge 6 generating propellant gases which flow out through an inner nozzle 8 concentrically arranged with respect to 2,989,919 Patented June 27, 1961 Ice the nozzle 7 of the first propellant charge. A rocket motor wall 9 separates the two propellant charges 5, 6, thus providing for the ignition of either one or both of such charges 5, 6, to obtain different firing rates of speed.

A relief valve housing 11 is mounted upon the front wall of a firing chamber 10 enclosing the nose end of one of the propellant charges 5. The relief valve housing .11 has four radially acting valve plates 12, each of which is normally radially outwardly extended to close a relief aperture 12a in the firing chamber 10, each such valve plate 12 being secured in the aperture closing position and prevented from moving radially inwardly by a guide piston 13 slidably supported within the relief valve housing 11 for movement between the normally rearwardly disposed position shown in FIGURE 2 and a forwardly extended position as shown in FIGURE 3. A bursting charge 14 mounted within the relief valve housing 11, upon ignition, acts against the guide piston 13 to force it forwardly toward the nose end of the depth charge, thus freeing the valve plates 12 for radially inward movement to the position shown in FIGURE 3, thus opening the respective apertures 12a to provide communication between the interior of the firing chamber 10 of one of the propellant charges 5 and two sets of forwardly extending relief conduits.

As is shown in FIGURE 1 of the drawing, each set of relief conduits opens forwardly through the nose end of the depth charge, and each such relief conduit includes an inner tube 15, 16. The tubes are insulated from the TNT charge 2 by means of air spaces between the inner tubes 15, -16 and outer tubular walls 17, 18, respectively. At their front ends, each of the inner tubes 15, 16 is provided with a nozzle 19, 20 respectively.

It will now be recognize that in actual use, ignition of one of the charges 5, 6 will produce a slower speed than the ignition of both of such charges 5, 6. However, a still lower speed may be obtained by setting the bursting charge 14 to ignite simultaneously with the ignition of a first propellant charge 5, thus allowing some of the propellant gases to escape outwardly through the opened apertures 12a and the relief conduits at the front end of the depth charge. As a result, whether the second propellant charge 6 is ignited or not, the forward speed of the depth charge attributable to the ignition of the first propellant charge 5 will be effectively curtailed by the escape of propellant gases outwardly through the relief conduits.

It will also be recognized that suitable control means may be provided for selecting the particular propellant charges 5, 6 to be ignited as well as the bursting charge 14 controlling the operation of the relief valve.

While this invention has been described with particular reference to the construction shown in the drawing, it is to be understood that such is not to be construed as imparting limitations upon the invention, which is best defined by the claims appended hereto.

Having thus described our invention, we claim as new and desire to secure by Letters Patent:

1. A depth charge comprising, in combination, an outer casing having a forward nose end and a rear tail end, a rocket motor mounted within said casing having a propellant charge storage chamber, a nozzle assembly having one end in communication with said chamber and an opposite end opening outwardly through said rear end of said casing, a relief valve carried by said motor communicating with said chamber, said relief valve including a housing having at least one aperture, a valve plate overlying said aperture, -a guide piston slidably supported within said housing for movement relative to said valve plate normally maintaining said valve plate in a closed position with said aperture, a propellant gas relief conduit communicating at one end with said relief valve and at the opposite end opening outwardly through said nose end of said casing, and a positioning busting charge acting between said housing and said guide piston of the valve for dislodging said piston from said plate upon firing to release said valve plate from closing engagement with said housing aperture to provide communication between said chamber of the casing and said relief conduit through said aperture, said relief valve controlling the flow of propellant gases through said relief conduit to adjust the propulsion velocity of said depth charge by the exhaustive propellant gases of said nozzle assembly.

2. A depth charge as set forth in claim 1, wherein said nozzle assembly comprises a set of concentrically arranged rearwardly opening nozzles each having a separately controlled firing chamber, said relief valve being associated with at least one of said nozzles.

3. A depth charge as set forth in claim 2, wherein said casing encloses a bursting charge intermediate said nose end and said relief valve, and said relief conduit comprises at least one tube assembly extending through said bursting charge, each tube assembly including an inner tube and an outer tube in concentric spaced apart relationship defining an air space insulating said inner tube from said bursting charge, and said inner tube being connected to said relief 'valve for conducting propellant gas to said nose of said casing.

4. A depth charge as set forth in claim 3, wherein said housing includes a plurality of apertures, and a separate plate carried by said housing for each said aperture, said guide piston simultaneously acting upon all of said plates.

References Cited in the file of this patent UNITED STATES PATENTS 2,850,976 Seifert Sept. 9, 1958 2,941,470 Jasse June 21, 1960 

